OK I know I am not the first to do this, someone had to clue me in, but instead of plugging, crimping, or otherwise disconnecting the vacuum line under the car, just unplug the actuator in the trunk in front of the drivers side tail light. I was a little unclear as to how this works, but it's dead...

I'm a new e90 owner. Just picked up a sedan with a sports package and 47K miles. I'm loving it.

Anyway, I owned an e36 M3 and it didn't have the flap, but the same year 328i had the flap. It was on the 328i for sound control and to make the cats warm up a little faster.
I started my e90 cold and noticed for the first 40-50 seconds the flap was closed. I don't know if it closes back up or not. It could just be a cold start function.

I know that there are no performance exhaust systems that have this.
I didn't do either the ball bearing/golf tee or unplug the connector. Unplugging the connector may register a fault because you have opened the circuit. Whether or not it matters is another story.

I went on eBay and did a search for the following after reading the first couple of pages:
PINCH VALVE CLAMP

I bought a couple for ~$3.
I'll put it on the hose inside the panel in the trunk.

I did this yesterday as well on my 2011 335i xDrive Coupe (automatic) and it sounds AMAZING! i did notice that the gas in the car started to drop in MPG for some reason, but i think its because i was in traffic and just happened to pay attention to it a bit more then usual lol

Hey did it show any errors after that? Cuz I do too have 2011 335i and I don't want the dealer to find out. : thanks

I love the difference in sound when unplugging the actuator, especially the gurgle on the decel. It will throw a hidden code, not a big deal. However, I've been dealing w/o2 sensor codes for some time and, after getting a carbon cleaning, changing plugs, and replacing all o2 sensors, I swear unplugging the actuator had something to do w/throw these codes. I've done all kinds of testing w/leaving it plugged vs unplugging and doing spirited driving under both circumstances and so far, 2wks later w/it plugged, the codes have not returned. Call it coincidental, but for me, there's some sort of link b/tween that actuator and the 02 codes. Oh, how I miss the sound, but oh how I can't stand getting those codes. I may wait another week or two and unplug it again, do some drives, and see if the codes come back. If they do, there's definitely a link. As for the golf-t mod and the clamp mod, I didn't notice any difference.

So, for those of you contemplating unplugging it - go for it! I'm running a stock setup w/catless downpipes and definitely noticed a difference in sound.

We had this valve on VW R32s and a lot of guys used medical supply clamps on the vacuum tubing, you can turn the mod on and off by pressing the clamp. A lot of medical supply places give free samples online:

did this and got a service engine soon light after about 500 miles with it unplugged.

Has to be a coincidence. Say you get a DINAN exhaust, which is endorsed by BMW and is covered under their manufacturer warranty. The DINAN exhaust has NO actuator flap and does not control which pipe exhaust comes out of. The actuator is mostly a sound dampener and slightly warms the cats up faster. After that the actuator is mostly for sound. Just my .02 but ready with firesuit.

Has to be a coincidence. Say you get a DINAN exhaust, which is endorsed by BMW and is covered under their manufacturer warranty. The DINAN exhaust has NO actuator flap and does not control which pipe exhaust comes out of. The actuator is mostly a sound dampener and slightly warms the cats up faster. After that the actuator is mostly for sound. Just my .02 but ready with firesuit.

It is possible that it could be a conicidence. I mean 500 miles is a while. I would imagine it would have triggered the SES sooner. I scanned with my Bav Tech and I had no engine fault codes or shadow fault codes. I short tested all modules and had no codes related to the engine. Cleared all other misc codes (radio, rain sensor, bluetooth, etc...) and reset the ECU. I drove the car for 25 miles and the SES light is still on. Not sure how to clear it. I just don't undertsand why Bav Tech is not picking up a code for the SES......